The objective of this study is to examine the cancer mortality experience in the United States relative to cancer etiology. Special emphasis is placed upon the selection of areas in the U.S. for intensive study. Publications from this area of interest have facilitated the design of ongoing analytical investigations to test specific etiologic hypotheses. Included among these are areas in the Southern U.S. with excessive rates of lung and oral cancer, in Nebraska for colon cancer, rural New England for bladder cancer, and in Maine where areas with excessive lung cancer rates have been detected. An analysis of characteristics that may influence this geographic variation of cancer was undertaken. In both sexes a large urban effect was observed for cancers of the nasopharynx, larynx, colon and rectum. The urbanization effect for colon cancer, however, disappeared when we controlled for social class. Lung cancer rates for white males and females were analyzed, and the findings suggest the influence of community air pollution from industrial emissions containing inorganic arsenic. We are continuing to expand our data sets, both of reported deaths and measures of exposure.